Injection element

ABSTRACT

Embodiments of the invention relates to an injection element having an inner element with a first outlet opening and an outer element. The outer element includes at least one second outlet opening structured and arranged for receiving and injecting fuel in a combustion space, and arranged coaxially to the first outlet opening. The outer element further includes third outlet openings composed of bores structured and arranged for forming a cooling liquid film layer, wherein the bores are arranged coaxially to the first outlet opening and the at least one second outlet opening.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application a continuation application of U.S. applicationSer. No. 10/579,201 filed May 12, 2006, which is a National StageApplication of International Application No. PCT/DE2004/002430 filedNov. 3, 2004, which published as WO 2005/049998 A1 on Jun. 2, 2005, thedisclosures of which are expressly incorporated by reference herein intheir entireties. Further, the present application claims priority under35 U.S.C. §119 and §365 of German Application No. 103 53 423.7 filedNov. 15, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an injection element, in particular for arocket drive, with an inner element with a first outlet opening and anouter element arranged coaxially thereto with at least one second outletopening arranged coaxially to the first outlet opening for receiving andinjecting fuel in a combustion space.

2. Background Description

Injection elements are used in a rocket drive for the mixturepreparation and for ensuring an optimal combustion in a combustion spaceof the rocket drive.

An injection element in coaxial construction for operation with twohypergolically reacting fuels is known, e.g., from DE 43 05 154 C1. Withthis injection element, the combustion fuel flow fed separately to thecombustion chamber is divided by means of a flow divider provided withbores, into several individual flows distributed over the circumferenceof the feed channel. This is to render possible a stable combustionwithout relevant pressure fluctuations.

Furthermore, an injection element is known from DE 101 30 355 A1 inwhich a fuel flow fed to a combustion chamber is divided and the twopartial flows thus produced are injected into the combustion chamber ina separated manner. The injection hereby occurs in the form of twohollow cone flows coaxial to one another. An optimal droplet preparationwith different droplet size in the two hollow cone flows can thus beachieved, which render possible special combustion zones with differentcombustion behavior or a gradual combustion of the fuel.

DE 195 15 879 C1 describes an injection element in bicoaxialconstruction, i.e., the injection element comprises an inner elementwith a first outlet opening to form a conical oxidant jet and an outerelement arranged coaxially thereto with further second outlet openingsin the form of passage channels to form fuel jets.

In many cases it is necessary to create a zone for cooling an area ofthe combustion chamber close to the wall. In order to achieve this, inpart the integration is resorted to of additional injection elementsembodied especially for this purpose. These can be on the one handelements with liquid swirl and on the other hand also simple elementswith bores.

SUMMARY OF THE INVENTION

The aim of the present invention is now to create an injection element,in particular for a rocket drive, which at the same time renderspossible the formation of a cooling liquid film layer for the injectionof fuel in a combustion space.

According to the invention, the injection element includes an outerelement having third outlet openings in the form of bores for forming acooling liquid film layer. The bores are arranged coaxially to the firstand second outlet openings. The invention is also directed to aninjection element having an inner element with third outlet openings inthe form of bores for forming a cooling liquid film layer. The bores arearranged coaxially to the first and second outlet openings.

One important concept of the invention lies in providing bores in aninner or an outer element of the injection element, which bores are usedto separate the fuel necessary for a cooling liquid film layer. Theadvantage of such an injection element is that elements already presentof conventional injection elements are used to create a fuel-rich oroxidizer-rich zone. Furthermore, only one element is required to form acooling film area, and additional elements are not necessary. Inaddition, there is the possibility of creating two zones in thecombustion space with the injection element according to the invention.Furthermore, a gradual reaction (combustion) can be achieved with theinvention. Finally, the invention is suitable for use in a wideoperating range with regard to a mixing ratio of fuel.

The invention now relates to an injection element, in particular for arocket drive, with an inner element with a first outlet opening and anouter element arranged coaxially thereto with at least one second outletopening arranged coaxially to the first outlet opening for receiving andinjecting fuel in a combustion space. According to the invention, theouter element has in addition third outlet openings in the form of boresfor forming a cooling liquid film layer, which bores are arrangedcoaxially to the first and second outlet openings.

In particular, the outer element can have a swirler space for impressinga swirl in the fed fuel flow, in which the bores are provided. In thiscase, fuel for forming the cooling liquid film layer is split off viathe bores in the swirler space. Swirlers are known, e.g., from DE 101 30355 A1 already mentioned at the outset and are also referred to there asa swirl insert.

Preferably the bores are provided in a tapering area of the swirlerspace. The bores can thus receive fuel particularly efficiently.

The bores can be arranged in the outer element such that the influenceof the cooling liquid film layer formed through the bores on the fuelinjecting into the combustion space is as slight as possible. In otherwords, the bores can be aligned such that the cooling liquid film layerand the fuel injecting into the combustion space just after entry intothe combustion space do not touch one another or mix.

The bores can change over into an annular gap to generate a swirl. Inthis case a cooling liquid film layer is formed with a swirl, which canhave an advantageous effect on the formation of an optimal mixture inthe combustion space.

The invention further relates to an injection element, in particular fora rocket drive, with an inner element with a first outlet opening and anouter element arranged coaxially thereto with at least one second outletopening arranged coaxially to the first outlet opening for receiving andinjecting fuel into a combustion space, in which according to theinvention the inner element has third outlet openings in the form ofbores for forming a cooling liquid film layer, which bores are arrangedcoaxially to the first and second outlet openings.

With this type of injection element, a partial premixing takes placethat is of major importance for an optimal combustion, particularly inthe case of elements with hollow cones of injected fuel that do notoverlap.

With the two types of injection elements explained above, according tothe invention the bores can be distributed in particularly uniformlyover the entire circumference of the outer or of the inner element. Aconical cooling liquid film is thus created. This is expedient inparticular with drives with only one injection element (single-elementchambers). With such drives the conical liquid film then serves to coolthe inner wall of the combustion space and avoids an enrichment ofexcess fuel during the phase of the ignition in the area of thecombustion space close to the wall. This is very important, particularlywith short-term operations, and greatly reduces the danger of thedeposit of too much residue such as, e.g., soot on the inner wall of thecombustion chamber. As already mentioned, a two-zone combustion can becreated above all by only one injection element.

In particular when several injection elements are used, it is moreadvantageous if the bores are distributed in particular uniformly overonly a part of the circumference of the outer or inner element.Preferably the bores should then be arranged in the part of thecircumference that lies adjacent to the inner wall of the combustionspace so that the liquid film layer exiting from the bores sprays in thedirection of the inner wall.

With a preferred embodiment with simple bores for feeding a component,the bores are preferably aligned such that fuel jets exiting from themare mixed with the component jets leaving the components feed bores. Apremixing of fuel and component thus occurs through which a dropletformation already takes place early. This has an advantageous effect inthe main mixing with a hollow cone of a swirler element.

Finally the invention relates to the use in a rocket engine that has acombustion space. The rocket engine is characterized in that it has atleast one injection element according to the invention.

In particular the at least one injection element according to theinvention is arranged with the rocket engine such that the coolingliquid film layer exiting from it is directed at least in part towardsthe combustion space inner wall.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and application possibilities of the presentinvention are revealed by the following description in connection withthe exemplary embodiments shown in the drawings.

The terms used in the list of reference numbers at the end and thereference numbers assigned thereto are used in the specification, in theclaims, in the abstract and in the drawings. The drawings show:

FIG. 1A A first exemplary embodiment of an injection element accordingto the invention in cross section;

FIG. 1B A second exemplary embodiment of an injection element accordingto the invention in cross section;

FIG. 2A A third exemplary embodiment of an injection element accordingto the invention in perspective cross section;

FIG. 2B A fourth exemplary embodiment of an injection element accordingto the invention in perspective cross section;

FIG. 2C The front face of the injection element shown in FIG. 2A in planview;

FIG. 2D The front face of the injection element shown in FIG. 2B in planview;

FIG. 3 An arrangement of several injection elements in the combustionspace of a rocket engine;

FIG. 4 A fifth exemplary embodiment of an injection element according tothe invention in cross section;

FIG. 5 A sixth exemplary embodiment of an injection element according tothe invention in perspective cross section; and

FIG. 6 A seventh exemplary embodiment of an injection element accordingto the invention in perspective cross section.

The same and functionally the same elements can be provided with thesame reference numbers below.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1A shows in cross-sectional representation an injection element 10with an inner element 12 and an outer element 14. Inner and outerelement 12 or 14 are arranged coaxially to one another. Both elementsreceive fuel under high pressure, which fuel is injected through eachelement respectively in the form of a hollow cone into a combustionspace (not shown) of a rocket drive. The fuel is injected via feed bores60 and 62 into the inner or outer element 12 or 14. Moreover, the outerelement 14 has a swirler space 18 in order to give the fuel a swirl.

FIG. 2A shows the injection element 10 from FIG. 1A in a perspectivecross-sectional representation. Here the front face 30 of the injectionelement 10 can be seen clearly from which the fuel exits and is injectedinto the combustion space.

The outer element 14 has several bores 16 in its outer wall, which boresbegin in the tapering area 20 of the swirler space 18 and end in thefront face 30 facing the combustion space. The bores 16 receive the fuellocated in the swirler space 18 and feed the received fuel to thecombustion space in the form of another hollow cone. The bores 16 arealigned such that the fuel sprays into the combustion space in the formof a hollow cone that opens in the direction of the inner wall of thecombustion space in order to cool the inner wall.

FIG. 1B shows another injection element 11 in cross section, whichelement is essentially similar to the injection element 10 of FIG. 1A,in which, however, inclined bores 24 are provided in the outer element15, which bores end in an annular gap 22 of the outer element 15. Withthis exemplary embodiment the fuel is injected via the annular gap 22with a swirl into the combustion space. To this end the bores 24 areinclined in two levels. FIG. 2B shows this exemplary embodiment in aperspective cross-sectional view. Through the inclination of the bores24, the fuel is already injected into the annular gap 22 with a swirl.

FIGS. 2C and 2D show the front faces 30 and 32 of the two exemplaryembodiments of the injection elements 10 or 11 shown in FIG. 1A, 2A or1B, 2B. With the first exemplary embodiment 10 in FIG. 2C a total ofeight bores 16 are uniformly distributed over the circumference of thefront face 30, i.e., the bores 16 are equally distanced from oneanother. With the second exemplary embodiment 11 in FIG. 2D four bores16 distributed uniformly over the circumference of the front face 32discharge into the annular gap 22. Both injection elements 10 and 11 aresuitable as single elements for a combustion space or a combustionchamber.

FIG. 3 shows the arrangement of several injection elements 28 and 34 ina combustion chamber of a rocket engine. The injection elements labeled34 are conventional injection elements that serve only to inject fuelinto the combustion space. Although the injection elements 28 accordingto the invention likewise serve to inject fuel, at the same time theyserve to form a liquid film layer cooling the combustion space innerwall 26. They differ from the exemplary embodiments 10 and 11 explainedabove in that bores 16 are provided only on the part of thecircumference of the front face of these injection elements 28 that isarranged directly adjacent to the combustion space inner wall 26, i.e.,in the area of the circumference of the front face close to the wall.Fuel is thus sprayed from the bores 16 in the direction of thecombustion space inner wall in order to cool it. This exemplaryembodiment is suitable for engines with several injection elements asshown. Inhomogeneities can be influenced or correspondingly orientedthrough a corresponding remaining run length of the swirler space.

FIG. 4 shows in cross section another exemplary embodiment of aninjection element 36 that has an inner element 38 and an outer element40 arranged coaxially thereto. In this exemplary embodiment bores 42 areprovided in the inner element 38, which bores end at the front face 43.The bores 42 are aligned such that the fuel thus split off from theinner element 38 mixes with the fuel injected into the combustion spacethrough the outer element 40 (fuel hollow cone 46). Through this apartial premixing takes place which has an advantageous effect inparticular with elements that form non-overlapping fuel hollow cones 44and 46 as in the exemplary embodiment shown.

FIGS. 5 and 6 finally show injection elements 48 and 50 that areprovided with component feeds, more precisely with bores 52 or 54 forfeeding a component. FIG. 5 shows an “unlike triplet” in which threeliquid jets intersect (at reference number 56). In contrast FIG. 6 showsan “unlike doublet” in which two liquid jets intersect (at referencenumber 58). Through the “intersection” of the jets a pre-mixing occursand thus a droplet formation, which has a favorable effect on the mainmixing with the hollow cone of the swirler element.

LIST OF REFERENCE NUMBERS

-   10 Injection element-   11 Injection element-   12 Inner element-   14 Outer element-   15 Outer element-   16 Bore-   18 Swirler space-   20 Tapering area of the swirler space 18-   22 Annular gap-   24 Inclined bore-   26 Combustion space inner wall-   28 Injection element-   30 Front face of the injection element 10-   32 Front face of the injection element 11-   34 Injection element-   36 Injection element-   38 Inner element-   40 Outer element-   42 Bores-   44 Inner fuel hollow cone-   46 Outer fuel hollow cone-   48 Injection element-   50 Injection element-   52 Bores for feeding a component-   54 Bores for feeding a component-   56 Intersection of three liquid jets-   58 Intersection of two liquid jets-   60 Feed bore for fuel-   62 Feed bore for fuel

What is claimed is:
 1. An injection element, comprising: a front facesurface; an inner element with a first outlet opening structured andarranged for receiving and injecting a first portion of fuel; an outerelement, comprising: at least one second outlet opening structured andarranged for receiving and injecting a second portion of fuel from theinjection element into a combustion space, and arranged coaxially to thefirst outlet opening; and third outlet openings radially beyond the atleast one second outlet opening composed of bores structured andarranged for forming downstream of the injection element in a fuel-flowdirection a cooling liquid film layer, wherein the bores are arrangedalong a ring, which is coaxial to the first outlet opening and the atleast one second outlet opening, and the bores are structured andarranged to supply the cooling liquid film layer in anoutwardly-directed direction relative to a longitudinal axis of thefirst outlet opening upon exiting the injection element, wherein atleast two of the first outlet opening, the at least one second outletopening and the third outlet openings are arranged on the front facesurface, wherein the injection element is a rocket drive injectionelement, wherein the bores open to the combustion space, and wherein thesecond portion of fuel does not traverse the first outlet opening. 2.The injection element according to claim 1, wherein the outer elementfurther comprises a swirler space in which the bores are located.
 3. Theinjection element according to claim 2, wherein the swirler spacecomprises a tapering area in which the bores are located.
 4. Theinjection element according to claim 2, wherein the bores are arrangedand aligned in the outer element such that a cooling liquid film layerand a fuel injected into the combustion space do not touch one anotheror mix just after entry into the combustion space.
 5. The injectionelement according to claim 1, wherein the outer element furthercomprises an annular gap, and wherein the bores connect with the annulargap to generate a swirl.
 6. The injection element according to claim 1,wherein the bores are uniformly distributed over an entire circumferenceof the outer element.
 7. The injection element according to claim 1,wherein the bores are uniformly distributed over a portion of an entirecircumference of the outer element.
 8. An injection element, comprising:a front face surface; an inner element with a first outlet opening; anouter element comprising component feed bores fluidly coupled to a firstliquid source, the inner element further comprising bores fluidlycoupled to a second liquid source and open to a combustion space,wherein the bores are arranged along a ring, which is coaxial to thefirst outlet opening to surround the first outlet opening, wherein thebores and the component feed bores are arranged such that liquid jetsexiting from the bores mix with liquid jets exiting from the componentfeed bores, wherein at least two of the first outlet opening, thecomponent feed bores, and the bores are arranged on the front facesurface, and wherein the injection element is a rocket drive injectionelement.
 9. The injection element according to claim 1, wherein theouter element is arranged coaxially with the inner element.
 10. Aninjection element, comprising: a front face surface; an inner elementcomprising a first outlet opening; an outer element with at least onesecond outlet opening structured and arranged for receiving andinjecting fuel from the injection element into a combustion space, andarranged coaxially to the first outlet opening; the inner elementfurther comprising third outlet openings composed of bores fluidlycoupled to a liquid source and structured and arranged for formingdownstream of the injection element in a fuel-flow direction a coolingliquid film layer, wherein the bores are arranged along a ring, which iscoaxial to the first outlet opening and the at least one second outletopening to surround the first outlet opening, and the bores arestructured and arranged to supply the cooling liquid film layer in anoutwardly-directed direction relative to a longitudinal axis of thefirst outlet opening upon exiting the injection element, wherein atleast two of the first outlet opening, the at least one second outletopening and the third outlet openings are arranged on the front facesurface, wherein the injection element is a rocket drive injectionelement, and wherein the bores open to the combustion space.
 11. Theinjection element according to claim 10, wherein the bores are uniformlydistributed over an entire circumference of the inner element.
 12. Theinjection element according to claim 10, wherein the bores are uniformlydistributed over a portion of an entire circumference of the innerelement.
 13. The injection element according to claim 10, wherein theouter element is arranged coaxially with the inner element.
 14. A methodof injecting fuel from an injection element into a combustion chambercomprising: guiding a first portion of fuel into the combustion chamberthrough a first outlet opening of the injection element; guiding asecond portion of fuel into the combustion chamber through a secondoutlet opening of the injection element arranged coaxially with thefirst outlet opening; and forming downstream of the injection element ina fuel-flow direction a cooling liquid film layer in the combustionchamber through bores arranged to coaxially surround the first outletopening, and structured and arranged to supply the cooling liquid filmlayer in an outwardly-directed direction relative to a longitudinal axisof the first outlet opening upon exiting the injection element whereinthe second portion of fuel does not traverse the first outlet opening.15. The method according to claim 14, wherein the cooling liquid filmlayer is directed at least in part towards a combustion space innerwall.
 16. The method of claim 14, wherein the bores are arranged tocoaxially surround the second outlet opening.
 17. The method of claim14, wherein fuel for forming the cooling liquid film layer is suppliedfrom the fuel guided to the first outlet opening.
 18. The method ofclaim 14, wherein fuel for forming the cooling liquid film layer issupplied from the fuel guided to the second outlet opening.
 19. Theinjection element according to claim 1 in combination with a combustionchamber, wherein the third outlet openings are structured and arrangedfor forming the cooling liquid film layer on a wall of the combustionchamber.
 20. The injection element according to claim 10, in combinationwith a combustion chamber, wherein the third outlet openings arestructured and arranged for forming the cooling liquid film layer on awall of the combustion chamber.
 21. The injection element according toclaim 1, wherein each of the first outlet opening, the at least onesecond outlet opening and the third outlet openings are arranged on thefront face surface.
 22. The injection element according to claim 10,wherein each of the first outlet opening, the at least one second outletopening and the third outlet openings are arranged on the front facesurface.
 23. The injection element according to claim 8, wherein thebores and the component feed bores are structured and arranged such thatone liquid jet exiting from a respective bore mixes with two liquid jetsexiting from two respective component feed bores such that three liquidjets intersect to form an unlike triplet.
 24. The injection elementaccording to claim 8, wherein the bores and the component feed bores arestructured and arranged such that one liquid jet exiting from arespective bore mixes with one liquid jet exiting from a respectivecomponent feed bore such that two liquid jets intersect to form anunlike doublet.